Nitro-PAH compounds in the atmosphere of Sao Paulo, Brazil
Abstract
Nitrated polycyclic aromatic hydrocarbons (nitro-PAH) are the chemical class with potent mutagenic compounds. These species are emitted from a wide range of combustion sources. Some compounds can be formed photo chemically via reactions of their parents PAH with OH or NO_3 radicals (in the presence of NO_2) in the gas phase as well as N_2O_5 or HNO_3 when parent PAH is associated with aerosols. In the tropics, an important source of particulate PAH and nitro-PAH is biomass burning used for clearings in forest and for making easier the harvesting of sugar cane. Brazil owns 25% of global sugar cane and is the major producer in the world. This burning produces soot, which remains for along time in the air and can cause respiratory diseases. This study was conducted in 3 cities in São Paulo State during sugar cane burning episodes. Back trajectories were calculated by University of São Paulo Trajectory Model for determination of air parcel trajectories over the sites. Atmospheric samples were collected on quartz fiber filters for 24 hours in high-volume sampler during one week. A Soxhlet apparatus filled with methylene chloride was used for extracting the filters. This residue was submitted to HPLC separation and the 3 obtained fractions (n-alkanes, PAH and nitro-PAH) were analyzed by both gas chromatography/flame ionization and gas chromatography/mass spectrometry detection. The isomers 2-, 3-, 8-nitrofluoranthene and 2-nitropyrene were identified and results show large differences between the sites. 2-nitropyrene/2-nitrofluoranthene ratios were calculated indicating the daytime reactions promoted by OH radicals.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....9322M